AJP - Heart and Circulatory Physiology, Vol 256, Issue 2 515-H519, Copyright © 1989 by American Physiological Society
Erythrocytes reduce liquid filtration in injured dog lungs
M. Onizuka, T. Tanita and N. C. Staub
Cardiovascular Research Institute, University of California, San Francisco 94143-0130.
In isolated, dog lung lobes with pulmonary vessels filled with different
liquids, we measured the rate of weight gain for 5 or 10 min at constant
alveolar and vascular pressures under zone 1 conditions (alveolar pressure
greater than vascular pressure). We used six different liquids: syngeneic
plasma, whole blood (hematocrit = 38 +/- 4%), 4% albumin in Krebs-Ringer
solution, washed red blood cells in Krebs-Ringer solution (hematocrit = 37
+/- 6%), and platelet-rich or platelet-poor plasma. We studied the lobes
under three conditions: immediate perfusion after removal (less than 30
min), delayed perfusion (2 h or more), or immediate perfusion after removal
from air-embolized animals. In lobes that showed low-filtration rate using
plasma [less than 0.5 g/(min x 100 g)] substitution of whole blood had no
effect on the filtration rate. In lobes that showed high-filtration rates
using plasma (delayed perfusion or deliberately injured using air emboli)
substitution of whole blood caused a dramatic decrease in the filtration
rate, restoring it to the level obtained in uninjured lobes. Platelets had
no effect. Thus the red cells specifically reduced abnormally high
filtration but did not affect normal filtration. There appear to be three
possible mechanisms: 1) red cells physically blocking large leaks; 2) red
cells settling on the filtration surface area (osmotic-barrier effect); 3)
red cells acting as reducing agents against active oxygen
metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)
